Add custom ops library_path to EP metadata (microsoft#25830)

## Summary
Adds EP metadata library path support to enable custom ops DLL
registration with proper path resolution.

## Changes
- Added `library_path` metadata key to EP metadata infrastructure
- Pass resolved library path directly to `EpLibraryProviderBridge`
constructor
- Simplified implementation per reviewer feedback (removed virtual
method complexity)
- Added `#include <utility>` for std::move compliance

## Purpose
Enables downstream applications (like onnxruntime-genai) to resolve
relative custom ops library paths using EP metadata, improving DLL
registration reliability.

## Files Modified
- `plugin_ep/ep_factory_provider_bridge.h`
- `plugin_ep/ep_library.h` 
- `plugin_ep/ep_library_plugin.h`
- `plugin_ep/ep_library_provider_bridge.cc`
- `plugin_ep/ep_library_provider_bridge.h`
- `utils.cc`

Author: psakhamoori

include/onnxruntime/core/session/onnxruntime_ep_device_ep_metadata_keys.h

@@ -12,4 +12,7 @@ static const char* const kOrtEpDevice_EpMetadataKey_Version = "version";
 // Prefix for execution provider compatibility information stored in model metadata.
 // Used when generating EP context models to store compatibility strings for each EP.
 // Full key format: "ep_compatibility_info.<EP_TYPE>"
-static const char* const kOrtModelMetadata_EpCompatibilityInfoPrefix = "ep_compatibility_info.";
+static const char* const kOrtModelMetadata_EpCompatibilityInfoPrefix = "ep_compatibility_info.";
+
+// Key for the execution provider library path (for dynamically loaded EPs)
+static const char* const kOrtEpDevice_EpMetadataKey_LibraryPath = "library_path";

onnxruntime/core/session/plugin_ep/ep_factory_provider_bridge.cc

@@ -4,6 +4,8 @@
 #include "core/session/plugin_ep/ep_factory_provider_bridge.h"
 
 #include "core/providers/shared_library/provider_host_api.h"
+#include "core/session/plugin_ep/ep_library_plugin.h"
+#include "core/session/onnxruntime_ep_device_ep_metadata_keys.h"
 
 namespace onnxruntime {
 OrtStatus* ProviderBridgeEpFactory::GetSupportedDevices(EpFactoryInternal& ep_factory,
@@ -20,6 +22,11 @@ OrtStatus* ProviderBridgeEpFactory::GetSupportedDevices(EpFactoryInternal& ep_fa
     auto* ep_device = ep_devices[i];
     if (ep_device) {
       ep_device->ep_factory = &ep_factory;
+
+      // Add library path to EP metadata if available
+      if (library_path_.has_value()) {
+        ep_device->ep_metadata.Add(kOrtEpDevice_EpMetadataKey_LibraryPath, library_path_->string());
+      }
     }
   }
 

onnxruntime/core/session/plugin_ep/ep_factory_provider_bridge.h

@@ -3,6 +3,10 @@
 
 #pragma once
 
+#include <filesystem>
+#include <optional>
+#include <utility>
+
 #include "core/framework/error_code_helper.h"
 #include "core/session/abi_devices.h"
 #include "core/session/abi_session_options_impl.h"
@@ -12,12 +16,14 @@
 namespace onnxruntime {
 class ProviderBridgeEpFactory : public EpFactoryInternalImpl {
  public:
-  ProviderBridgeEpFactory(OrtEpFactory& ep_factory, ProviderLibrary& provider_library)
+  ProviderBridgeEpFactory(OrtEpFactory& ep_factory, ProviderLibrary& provider_library,
+                          std::optional<std::filesystem::path> library_path = std::nullopt)
       : EpFactoryInternalImpl(ep_factory.GetName(&ep_factory),
                               ep_factory.GetVendor(&ep_factory),
                               ep_factory.GetVendorId(&ep_factory)),
         ep_factory_{ep_factory},
-        provider_library_{provider_library} {
+        provider_library_{provider_library},
+        library_path_{std::move(library_path)} {
   }
 
  private:
@@ -59,8 +65,9 @@ class ProviderBridgeEpFactory : public EpFactoryInternalImpl {
     return ep_factory_.CreateSyncStreamForDevice(&ep_factory_, device, stream_options, stream);
   }
 
-  OrtEpFactory& ep_factory_;           // OrtEpFactory from the provider bridge EP
-  ProviderLibrary& provider_library_;  // ProviderLibrary from the provider bridge EP
+  OrtEpFactory& ep_factory_;
+  ProviderLibrary& provider_library_;
+  std::optional<std::filesystem::path> library_path_;
 };
 
 }  // namespace onnxruntime

onnxruntime/core/session/plugin_ep/ep_library.h

@@ -23,6 +23,7 @@ class EpLibrary {
   virtual Status Load() { return Status::OK(); }
   virtual const std::vector<OrtEpFactory*>& GetFactories() = 0;  // valid after Load()
   virtual Status Unload() { return Status::OK(); }
+
   virtual ~EpLibrary() = default;
 
   ORT_DISALLOW_COPY_AND_ASSIGNMENT(EpLibrary);

onnxruntime/core/session/plugin_ep/ep_library_provider_bridge.cc

@@ -4,6 +4,7 @@
 #include "core/session/plugin_ep/ep_library_provider_bridge.h"
 
 #include "core/session/plugin_ep/ep_factory_provider_bridge.h"
+#include "core/session/plugin_ep/ep_library_plugin.h"
 
 namespace onnxruntime {
 Status EpLibraryProviderBridge::Load() {
@@ -26,8 +27,9 @@ Status EpLibraryProviderBridge::Load() {
   // to do this we need to capture `factory` and plug it in to is_supported_fn and create_fn.
   // we also need to update any returned OrtEpDevice instances to swap the wrapper EpFactoryInternal in so that we can
   // call Provider::CreateIExecutionProvider in EpFactoryInternal::CreateIExecutionProvider.
+
   for (const auto& factory : ep_library_plugin_->GetFactories()) {
-    auto factory_impl = std::make_unique<ProviderBridgeEpFactory>(*factory, *provider_library_);
+    auto factory_impl = std::make_unique<ProviderBridgeEpFactory>(*factory, *provider_library_, library_path_);
     auto internal_factory = std::make_unique<EpFactoryInternal>(std::move(factory_impl));
 
     factory_ptrs_.push_back(internal_factory.get());

onnxruntime/core/session/plugin_ep/ep_library_provider_bridge.h

@@ -21,9 +21,11 @@ namespace onnxruntime {
 class EpLibraryProviderBridge : public EpLibrary {
  public:
   EpLibraryProviderBridge(std::unique_ptr<ProviderLibrary> provider_library,
-                          std::unique_ptr<EpLibrary> ep_library_plugin)
+                          std::unique_ptr<EpLibrary> ep_library_plugin,
+                          std::optional<std::filesystem::path> library_path = std::nullopt)
       : provider_library_{std::move(provider_library)},
-        ep_library_plugin_{std::move(ep_library_plugin)} {
+        ep_library_plugin_{std::move(ep_library_plugin)},
+        library_path_{std::move(library_path)} {
   }
 
   const char* RegistrationName() const override {
@@ -53,6 +55,9 @@ class EpLibraryProviderBridge : public EpLibrary {
   // implement EpFactoryInternal::CreateIExecutionProvider by calling Provider::CreateIExecutionProvider.
   std::unique_ptr<EpLibrary> ep_library_plugin_;
 
+  // Library path for EP metadata
+  std::optional<std::filesystem::path> library_path_;
+
   std::vector<std::unique_ptr<EpFactoryInternal>> factories_;
   std::vector<OrtEpFactory*> factory_ptrs_;                // for convenience
   std::vector<EpFactoryInternal*> internal_factory_ptrs_;  // for convenience

onnxruntime/core/session/utils.cc

@@ -421,13 +421,14 @@ Status LoadPluginOrProviderBridge(const std::string& registration_name,
                      << (is_provider_bridge ? " as a provider bridge" : " as a plugin");
 
   // create EpLibraryPlugin to ensure CreateEpFactories and ReleaseEpFactory are available
-  auto ep_library_plugin = std::make_unique<EpLibraryPlugin>(registration_name, std::move(resolved_library_path));
+  auto ep_library_plugin = std::make_unique<EpLibraryPlugin>(registration_name, resolved_library_path);
   ORT_RETURN_IF_ERROR(ep_library_plugin->Load());
 
   if (is_provider_bridge) {
     // wrap the EpLibraryPlugin with EpLibraryProviderBridge to add to directly create an IExecutionProvider
     auto ep_library_provider_bridge = std::make_unique<EpLibraryProviderBridge>(std::move(provider_library),
-                                                                                std::move(ep_library_plugin));
+                                                                                std::move(ep_library_plugin),
+                                                                                resolved_library_path);
     ORT_RETURN_IF_ERROR(ep_library_provider_bridge->Load());
     internal_factories = ep_library_provider_bridge->GetInternalFactories();
     ep_library = std::move(ep_library_provider_bridge);